1. Field of the Invention
The present invention relates to putters. More specifically, the present invention relates to polymer-based putters.
2. Description of the Related Art
Conventional methods of manufacturing golf clubs include investment casting, forging and die casting. Inconsistent dimensions and weights are problems with conventional manufacturing techniques. Also, the inability to alter the club weight without changing the size and shape of the club head is another problem with conventional manufacturing techniques. Further, the conventional techniques require polishing to achieve an acceptable finish on the club heads, which results in the removal of mass from the club head. One major problem is the production time to manufacture club heads, which consumes two weeks on average to produce a club head. These problems are associated with manufacturing of putters, irons and woods.
The golf industry needs alternative means of manufacturing golf club heads. One example is set forth in PCT International Publication Number WO 99/29374 to Keelan for a Composite Putter Head, which claims priority to U.S. patent application Ser. No. 08/989,320 filed on Dec. 11, 1997. Keelan discloses that the club head is composed of a plastic material blended with a powder metal that is injection molded to create the club head. Keelan discloses using the following thermoplastic materials: ethylene vinyl acetate, polyurethane, polyolefin, polypropylene, and polyvinylchloride. The metal is added in a range of 50 to 95 percent of the weight of the club head.
Another example is Uebelhor, U.S. Pat. No. 6,086,484, which was filed on Mar. 20, 1998 for a Golf Putter Head. Uebelhor discloses a putter head with a U-shaped body and a block within the middle. The block has a lower specific gravity than the U-shaped body.
Yet another example is Rose et al., U.S. Pat. No. 5,951,412 originally filed in January of 1996 for a Golf Club, Particularly A Putter. The Rose patent discloses a center portion composed of a light metal material and the heel and toe portions composed of heavier metals. The metals are forged or cast to create the putter head.
Another example is Fernandez, U.S. Pat. No. 4,793,616 for a Golf Club, which was originally filed in 1984, discloses a lightweight composite material molded to a hard, high density material for distribution of mass. Fernandez discloses a composite shell with a high density insert composed of tungsten or some other high density material.
The present invention is an unique golf club that is manufactured from a novel process. The golf club of the present invention has an interior body composed of a high density material with an outer shell composed of a lower density thermoplastic injectable material.
The present invention allows for tight tolerances on the dimensions and shapes of golf club heads. It also allows for the weight of the golf club head to be altered quickly and easily during the manufacturing process. The present invention also provides a golf club head that is essentially finished upon demolding. Further, the current process can take as little as two minutes to manufacture a golf club head. Further, the present invention allows for the feel, color and sound of the golf club head to be modified upon a change in the material of the outer shell. Also, the texture of the finished golf club head can be modified by modifying the mold for the outer shell.
One aspect of the present invention is a golf club head that includes an interior body and an outer shell. The interior body is composed of a first injectable material having a first density which is greater than 4.0 g/cc. The outer shell is disposed over the interior body. The outer shell is composed of a second injectable material having a second density which is less than the first density.
Another aspect of the present invention is a method for forming a golf club head. The method includes placing an interior body within a mold with the interior body composed of a first material having a first density that is greater than 4.0 g/cc. The interior body also has a shape substantially similar to the golf club head. The next step is injecting a second material into the mold to encompass the interior body and form an outer shell. The second material has a second density that is less than the first density. The outer shell has a thickness of at least 0.100 inch.
Having briefly described the present invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings.